The present invention generally relates to an assaying device and more specifically relates to an analyte assaying device with a multiple sample introduction system.
Devices for testing for the presence of single or multiple substances, (i.e. xe2x80x9canalytesxe2x80x9d) in a single fluid sample, for example a urine or blood specimen, are well known. The demand for inexpensive, accurate and simple to use devices for testing, or assaying, biological specimens has increased in recent years. Various commercial assaying devices are available for use in hospitals, clinics, research laboratories, at home and in the workplace. Following now are some specific, common examples illustrating the use of assaying devices. For example, in a hospital setting, patients are often subjected to massive dosages of antibiotics to defeat an infection, and thereafter a small amount of blood may be withdrawn from the patient and the serum assayed for determining if an appropriate amount of antibiotic is present in the blood. As another specific example, in a hospital emergency room where an overdose patient has impaired cognitive function, or is a small child unable to communicate, the type of drug overdosed may be quickly determined using an available assaying device in order to ensure correct administration of treatment. Assaying devices are commonly used in other settings as well. For example, many employers now routinely administer so called xe2x80x9cdrug testsxe2x80x9d to prospective and current employees in order to maintain a safe work environment. In addition, pregnancy and fertility test kits adapted for xe2x80x9cin homexe2x80x9d use, are now widely available to consumers. Such test kits include assaying devices which are, for the most part, accurate, and very easy to use.
A common form of assaying device is a lateral flow test device which generally includes a porous element of nitrocellulose or paper, typically in strip form, having chemical reagents striped or incorporated onto specific regions, or xe2x80x9czonesxe2x80x9d thereof. One zone may include a specific binding reagent for the analyte, bearing a visible label such as a colored latex particle. The labeled reagent is incorporated onto the porous element in a manner that allows it to freely migrate through the porous material, in the presence of a liquid specimen sample. Another zone, spatially distinct from the first zone, may include an unlabeled specific binding reagent having specificity for same analyte as the first zone, and which is capable of participating with the labeled reagent in either a xe2x80x9csandwichxe2x80x9d or xe2x80x9ccompetitionxe2x80x9d reaction. The unlabeled specific binding reagent may be firmly immobilized on the porous element such that it is not free to migrate through the porous material, even in the moist state. In a xe2x80x9csandwichxe2x80x9d type assay, any analyte present in the specimen sample will become labeled as it is carried through the porous element and bound, where its presence is manifested by a detectable color change.
Many such test devices for detecting body fluid components are capable of making not only qualitative, but also quantitative or semi-quantitative measurements. Thus, by observing a color change response after a certain period of time, an analyst can obtain not only a positive indication of the presence of a specific component, but also an estimate of how much of the component is present in the sample.
Assaying devices may take the form of a dip-and-read type device, in which one portion of the porous element is immersed in a specimen sample, such as in a collection cup, or a urine stream. May et al. U.S. Pat. No. 5,602,040 issued on Feb. 11, 1997, discloses such a dip-and-read type device which includes an elongated case having a porous test strip disposed within, and a protective, removable cap or shroud. The cap is used to cover a sample receiving member protruding from the casing, after the sample receiving member has been contacted with a urine specimen. Other assaying devices are designed to be placed horizontally on a table top and include a case enclosing a porous test element, the casing typically including a receptacle in which a measured amount of specimen sample is deposited using a syringe, for example.
Conventional assaying devices have also been developed which include multiple lateral flow test elements which allow for detection of more than one type of analyte in a single fluid specimen. For example, U.S. Pat. No. 5,976,895 issued to Cipkowski on Nov. 2, 1999 discloses such a device. The Cipkowski device includes a transparent container having a lid with a slit for receiving a single test card having multiple test strips. Procedure of use requires a test subject to fill the container with a urine specimen, and place the lid on the container. The test card with multiple strips is then manually inserted through the slit in the lid such that a portion of each strip is immersed in the specimen. Each strip absorbs some of the specimen. The card is left in the container for a period of time and test results are read on the test card by observation through the transparent container walls.
Although these and other assaying devices are generally easy to use in both a clinical and home setting, the procedures of their use are less than desirable in a situation where many different tests must be conducted on a regular, frequent basis, for example at a drug testing laboratory.
It would be highly desirable to be able to test a single fluid specimen for a number of different substances using a compact, unitary device which requires no measuring or timing. Moreover, it would be advantageous if such a device was designed to require minimal handling, was sanitary to use and did not require separate caps or coverings to prevent contamination of the laboratory work table.
The present invention provides a sample fluid test card device containing single or multiple test strips for assaying a fluid specimen. The present device promotes hygienic laboratory conditions, is easy to use, and facilitates the assaying process in comparison to currently available assaying devices.
Accordingly, an analyte assaying device with a unique sample introduction system is provided. The device enables automatic specimen volume measurement, automatic controlled specimen metering, no wet contact of the device with the laboratory counter top, controlled flow venting for preventing test strip flooding and other advantages features which facilitate assaying of a fluid specimen.
Generally, the device comprises a casing and means, disposed in the casing, for assaying a fluid specimen, for example, but not limited to a biological fluid specimen, for example urine. The assaying means preferably comprises a testing assembly including at least one test strip element, disposed within the casing. In one embodiment of the invention, the test assembly comprises multiple lateral flow test strips for enabling several different assays to be performed on a single fluid specimen. Each test element includes a sample introduction region and a detection region where chemical interactions take place to reveal a presence or absence of an analyte of interest depending upon the assaying test being performed. The test assembly preferably further comprises a sample pad for receiving the fluid sample, and an absorbent end pad. The sample pad may overlap the sample introduction region of each of the test elements. The fluid specimen absorbed by the sample pad then permeates and is absorbed by the sample introduction region of the test element and migrates into the detection region by capillary action. The absorbent end pad, provides means for absorbing any excess fluid or moisture in the casing before, during and/or after the assaying procedure.
The casing preferably comprises a cover, a base, a pocket portion and an observation portion. The cover and base form a substantially hollow cavity within the casing in which the testing assembly is disposed. Multiple frets are defined by interior surfaces of the cover and/or base in order to secure alignment of the test elements.
The observation portion of the casing defines at least one window opening for enabling observation of portions of the test elements. For example, multiple window openings may be provided for enabling observation of test results displayed on one or more portions of each of the testing elements. Alternatively, the casing may be at least partially transparent in order to enable visual observation of the test elements. For example the casing may include no window openings and may be made of a clear plastic material.
Importantly, the pocket portion defines a pocket sized to contain a predetermined volume of the fluid sample to be tested. In the multiple test element embodiment of the invention, the pocket is sized and adapted to contain at least a volume of fluid that is sufficient to run all of the multiple test elements to completion after a quick (e.g. between about one second and five seconds) dip into the test fluid. Consideration is given to any amount of fluid that will naturally be retained by the sample pad after the assaying procedure has run to completion.
The device in accordance with the present invention further includes means for automatic controlled metering of the fluid specimen onto the sample pad. More specifically, the pocket portion of the casing further includes a feed element having at least one feed inlet defined therein for providing fluid transfer between the pocket and the testing assembly. The feed element projects from the interior surface of the casing cover and provides pressure against the sample pad. Advantageously, the structure of the feed element and feed inlets and their relationship with the sample pad, assure a metered, controlled release of the fluid sample, thus preventing saturation of the test assembly and flooding of the casing cavity. This feature of the present invention functions to control specimen metering regardless of whether the device is vertically positioned or horizontally positioned, the importance of which will become better appreciated upon further review of the present description.
The pocket portion is preferably sized and shaped to facilitate capture of the predetermined volume of fluid when the pocket portion of the device is momentarily submerged in a fluid specimen, for example a urine specimen contained in a collection cup. The base and cover are sealed at adjoining edges thereof to prevent fluid from entering the casing from anywhere other than through the feed inlets in the pocket portion.
Another advantageous feature of the present invention includes support means, defined for example by a depending portion of the base, for propping or elevating the pocket portion of the casing when the device is placed on a level surface, in a substantially horizontal position, for example a laboratory counter top. This feature of the device is designed to enhance cleanliness of a laboratory in which many assaying procedures may be regularly conducted. More specifically, the support means is designed to prevent any xe2x80x9cwetxe2x80x9d contact of the pocket portion of the device, particularly after the pocket portion has been dipped or submerged in the fluid specimen. Advantageously, this allows a laboratory technician to dip or submerge the device in the collection cup in order to obtain the appropriate volume of fluid to run the test, and thereafter immediately place the device aside directly on the counter top without causing any wet contact between the device and the counter top. Moreover, with the present invention there is no need for special racks, hooks, support trays or other holders for supporting the device while the chemical reactions are taking place.
As an alternative procedure of use, the device may initially be placed on the laboratory counter top, in the horizontal position, and fluid specimen transferred from a source into the casing pocket by means of a pipette for example. The technician would simply fill the pocket without the need for any precise measurement, as the pocket is sized to contain the proper amount of fluid sample. The fluid sample will be absorbed at the appropriate rate from the supply held in the pocket.
Another feature of the present invention is means for facilitating manual handling of the device. For example the casing may be configured with appropriate recesses and/or textured gripping surfaces appropriately positioned to facilitate the manual handling of the device when the device is dipped into or otherwise submerged in the specimen.